Method and device for the steering of ships



A. FLETTNER METHOD AND DEVICE FOR THE STEERING 0F SHIPS Feb. 28, 1928. 1,661,114

Filed June 29. 1920 13 Sheets-Sheet l E In venior:

Feb."28, 1928. I 1,661,114

} A. FLETTNER 1 METHOD AND DEVICE FOR THE STEERING OF SHIPS Filed June 2 1920 13 Sheets-Sheet 2 In'uen Z01".-

Feb. 28, 1928. 1,661,114

, A. FLETTNER METHOD AND DEVICE FOR TEE STEERING 0F SHIPS Filed June 29. 1920 13 Sheets-$hedt 3 I nven taz':

Feb. 28, 1928. 1,661,114

A. FLETTNER METHOD AND DEVICE FOR THE STEERING OF SHIPS Filed 'June 29. 192d 13 Sheets-Shut 4 In ven tor:

Feb; 2a, 1928.

1,661,114 A. FLETTNER 7 METHOD AND DEVICE FOR THE STEERING 0F SHIPS Filed June 29. 1920 13 Sheets-Sheet 5 w l' EF Invenfor:

Feb. 2a, 1928. 1,661,114

A. FLETTNER METBOD AND DEVICE FOR THE STEERING OF SHIPS Filed June 29. 1920 l3 Sheets-Sheet 6 Inven Z02":

Feb. 28, 1928. 1,661,114

A. FLETTNER METHOD AND DEVICE FOR THE STEERING SHIPS Filed June 29, 1920 13 Sheets- Sheet 7 A. FLETTNER METHOD AND DEVICE FOR THE STEERING OF SHIPS Filed June 29. 1920 15 Sheets-Sign. 8

Feb. 2a, 1928. 1,661,114

In ven for:

Feb. 2a, 1928. v 1,661,114

A. FLETTNER METHOD AND DEVICE FOR THE STEERING 0F SHIPS Filed June 29. 1920 13 Sheets-sheaf. 9

I nven Z01".-

Feb. 28, 1928. 1,661,114

A. FLETTNER METHOD AND DEVICE FOR. THE STEERING OF SHIPS Filed June 9, 192d 15 Sheets-Sheet 10 In venior:

Feb. 28, 1928.

1,661,114 A. FLETTNER METHOD AND nsvxcn FOR THE sgmmme or sans Fil n 29. 1920 13 Sheets-Sheet 11 Feb. 28, 1928.

13 Sheets-Sheet 12 A. FLETTNER DEVICE FOR THE STEE Filed June 29, 1926 ffi ssqii asj mo.

A. FLETTNER METHOD AND DEVICE FOR THE STEERING 0F SHIPS Filed June 1920 15 Sheets-Sheet 1s Fb.2s,192s. 1,661,114

In venior:

Patented Feb. 28, 1928.

UNITED STATES 1,661,114 PATENT OFFICE.

ANTON FLETTNEB, 0F GBUNEWALD, NEAR BERLIN, GERMANY.

METHOD AND DEVICE FOR THE STEERING 0F SHIPS.

Application filed June 29, 1920, Serial No. 392,839, and in Germany June 16, 1917.

My invention relates to a method and devices for the steering of ships by the aid of which the service at the wheel is considerably simplified, the amount of force required in steering reduced to a fraction of that hitherto necessitated, and the steering efficiency its lf essentially increased.

In accordance with my invention the rudder is in general not operated directly, but is deflected by aid of one or a plurality of auxiliary rudders, the actuation of which requires but a very slight expenditure of force. In other words, the rudder is treated as though it were itself a ship, and the steering effected by means of a small auxiliary rudder, mounted on the main rudder near the rear edge thereof. According to the position this auxiliary. rudder is caused to assume, it will, acting under the force of the water current, shift the main rudder more or less either to larboard or to starboard, and thus effect the steering of the vessel. The size of the auxiliary rudder may stand in Y the same relation to that of the main rudder,

as this latter to the size of the vessel.

However, it is possible to go yet further,

and to cause also the auxiliary rudder to be steered by a second auxiliary rudder, the displacement of which requires still less expenditure of force, and so on.

Several forms of construction of the subject matter of my invention are shown diagrammatically by way of example in the ac companying drawings.

Fig. 1 is a perspective view of one form of the invention; Fig. 2 shows a modified form; Fig. 3 shows another modification for automatically maintaining the main rudder in the desired position; Fig. 4 shows an ar rangement for the same purpose as Fig. 3, a.

second auxiliary rudder also being used; Figs. 5 and 6 are side and top views respectively of amodification showing two auxiliary rudders; Fig. 7 shows two auxiliary rudders and operating means therefor; Fig. 8 shows one auxiliary rudder and a modified operating means therefor; Fig. 9 shows an arrangement for automatically maintaining the main rudder in the desired position; Fig. 10 shows an arrangement of a plurality of auxiliary rudders arranged in different horizontal planes; Fig. 11 shows a plurality,

of auxiliary rudders arranged in different vertical planes; Fig. 12 shows the main rudder made in several sections, each sectlon being operated by an auxiliary rudder; Fig. 13

shows a counter-balanced main rudder and a guard for the auxiliary rudder; Fig. 14

shows the main rudder more strongly counter-balanced than in Fig. 13; Figs. 15 and 16 are side and plan views respectively of a counter-balance for the main rudder; Fig. 17 shows another counter-balancing device for themain rudder; Fig. 18 shows still another counter-balancing device for the main another mounting means for the main rudder; Fig. 26 shows a still further mounting means for the main rudder; Figs. 27 and 28 show a plurality of auxiliary ruddersapd protective surfaces associated therewith; Fig. 29 is a modification showinga plurality of auxiliary rudders and protective surfaces therefor; Fig. 30 shows outlying auxiliary rudders operated by another auxiliary rudder and protecting surfaces for the rudders; Figs. 31 and 32 show different modifications for protecting the main and auxiliary rudders; Fig. 33 shows bow and stern rudders; Figs. 34 and 35' show specific shapes used for the auxiliary rudders; Fig. 36 is a modification, particularly for allowing reversal of the main rudder when the vessel is sailing aster-n; Fig. 37 is amodification of Fig. 36, the auxiliary rudder being mounted on a centrally disposed axis; Figs. 38, 39 and 40 show shapes for the rear edge of the main rudder and for the front edge of the auxiliary rudder; Fig. 41 shows a modification for allowing proper operation of the auxiliary rudder when sailing astern; Fig. 42 is a view of a detail of Fig. 41; and Fig. 43 is a modification of the auxiliary rudder for initiating the reversal of the main rudder. In the arrangements disclosed by F ig. 1,. there is arranged at.the rear edge of the freely movable main rudder 1, on a vertical spindle 3, an auxiliary rudder 2, which is operated by a sheave 4, mounted on the spindle of the main rudder by the aid of a rope or chain drive -5, and another sheave 6., On this auxiliary rudder being shifted over to starboard, the water current acting on its surface will force the main rudder to larboard, and vice versa. In other words, the

freely movable main rudder will follow exactly every movement of the sheave 4 and will turn through the same angle as this latter. As stated, the auxiliary rudder 2 may again be steered by a still smaller auxiliary rudder. However, the rudder 2 may also be arranged at some distance from the rear edge of the main rudder, as shown in Fig. 2, in which 1 denotes the main rudder, and 2 the auxiliary rudder.

It may further prove expedient to arrange an auxiliary rudder both at the front and the rear edge. The said auxiliary rudder may be disposed in an opening cut into the surface of the main rudder; it may, however, also be pivoted thereto, and this either at the end or at the side, or else be connected to said main. rudder by means of levers.

The reduction of the actual steering work required to be done is due to the fact that the arm of lever of the auxiliary rudder is longer than the arm of lever appertaining to the main rudder; i. e. longer than the distance of the centre of pressure from the rudder axis. \Vhen the auxiliary rudder is displaced, its surface is subjected to pressure, and it effects by means of its lever arm the motion of the main rudder. It thus follows, that the steering work to be effected may be immediately derived from the force or pressure acting on the auxiliary v rudder surface.

Experience has furthermore shown that special devices are required in order to set the main rudder by help of an auxiliary rudder correctly in every angular position that may be required at any time. For this could only be obtained directly if it were possible to nicely counterbalance the pressure :0 of the auxiliary rudder relatively to the counter pressure y exerted by the main rudder; in other words, if it were possible to determine the proper proportions of the main rudder relatively to the auxiliary rud der with absolute exactitude. A second condition would be that the pressure acting on the surface of the main rudder, in the case of a uniform increase of the angle of declination (i. e. the angle formed by the rudder and the longitudinal axis of the vessel), were to augment in the same proportion as the pressureacting on the surface of the auxiliary rudder.

It further must be taken into due consideration that in the case of balanced rudders, owing to the fact that at the commencement of the steering action the centre of pressure lies in front of the rudder axis, the rudder itself is in a state of unstable equilibrium and that therefore the auxiliary rudder, at the beginningof the displacement of the main rudder, in order to pre-- vent this latter from tilting, would be obliged to act directly counter to the main the vessel is running, and in particular during the steering operations, alterations in the current are.apt to arise, and therewith fluctuatlons of pressure, which might cause a continual change in the position of the rudder. I

Now, all these drawbacks can only be successfuly overcome by an arrangement which, as far as the counterbalancing of forces 00 and 3 is concerned, as also with regard to the attention to be paid to the mutual change of'the pressures or forces acting on both main and auxiliary rudders, will only make slight demands on the ingenuity of the constructing engineer, and which will to best ability restrict the necessity of maintaining an exact consonance or an upkeep of a definite proportion between the position and size of the auxiliary rudder and that of the main rudder.

An example for'an arrangement of this kind is shown diagrammatically in Fig. 3.

The freely movable main rudder 1 supports on its spindle 7 a toothed segment 8 which meshes with a toothed segment9like-,

Wise lodged on the said rudder. The segment 9 is linked on its one side to a transverse arm 10, arranged on the spindle of the auxiliary rudder 2, by means of a connecting rod 11. v

The steering operation is effected as follows: On the segment 8 being deflected, say, for about 2, thenprovided the proportion of the diameters of the toothed segments 8.9

relatively to each other, be as, for example,

4:1-the smaller toothed segment 9 will be displaced, and with it the auxiliary rudder 2 connected with it, fora distance of 8. By these means, said rudder 2* is subjected to pressure, and, in its turn, it effects the deflection of the main rudder 1. Since, however, the toothed segment 9 at the same time rolls along the toothed segment 8, the auxiliary rudder while causing the deflection of the main rudder is automatically turned back into its initial position, and this for a distance .until the forces are completely balanced.

Now the same result would have been obtained if the proportion of the diameters of the two toothed segments had been fixed at the .value 1 or thereunder. For also in such a case, on the main ruddenbeing deflected,

the auxiliary rudder is rotated back. The

advantage of the larger proportions resides above all in the fact that on initiating the steering operation there is attained a surplus of steering force by the auxiliary rudder, which offers the full security that the main rudder will reliably attain the position desired. In a like favorable manner this said excess of force will be able to counteract any deflection of the main rudder'beyond its limit. For, were this contingency to arise,

then the segment 9 would continue to roll which this latter will be deflected, say, for d 2, the auxiliary rudder will be shifted for 8 into a counter pressureposition. For this reason, the rudders will attain and retain with utmost exactitude the position they are desired to assume.

Here, too, the auxiliary rudder for its part may be steered, if desired, by a still smaller auxiliary rudder, which may be operated through the axis of the main rudder, this rudder itself, and finally through the axis of the first auxiliary rudder. Such an arrangement is shown by way of example .in Fig. 4.

In this arrangement a shaft 13 is disposed within the hollow spindle 12 of the main rudder 1, which shaft is coupled by means of toothed wheels 14, 15 to a shaft 16 disposed in the hollow spindle 17 of the first auxiliary rudder 2, and adapted to act upon the spindle of the second auxiliary rudder 20 by means of the toothed wheels 18, 19. The main rudder 1 and the first auxiliary rudder 2 are freely movable, whereas the second auxiliary rudder 20 is rigidly connected to its toothed wheel 19, and is thus operated or steered immediately from the shaft 13. On it being shifted, say, to larboard, it will cause the first auxiliary rudder 2" to deflect to starboard, and therewith the main rudder 1 to deflect to larboard again.

In the place of toothed segments, use may, of course, also be made of toothed couplings. levers, rope or chain drives. or any other form of transmission arrangements.

A transmission arrangement bymeans of a rope is illustrated by way of example in Figs. 5 and 6 in elevation and plan view, re spectively. On. a rudder spindle 21 there is mounted a rope pulley 22, and on another spindle 23, the rope pulleys 24 and 25. The spindle of the second auxiliary rudder 20 shown in Figs.

. carries a pulley 26. A rope 27 is run crosswise over the pulleys 22 and 24, and a rope 28 in the like manner across the pulleys 25 and 26. y Fig. 7 shows a modified form of arrangement, in which the rope 29 is led from the pulley 30 of the spindle 31 of the main rudder, across the pulleys 32, 33, then right through the hollow spindle of the first auxiliary rudder 2", then on the stationary pulley 34 of the second auxiliary rudder 20*, and across the pulleys 35, 36, finally back to the pulley 30. As a the position of the first auxiliary rudder does not, as in the case of the arrangement 4 and 5, immediately, affect the position of the second auxiliary rudder, but rather this latter is acted upon directly,

by any change of position assumed on the part of the main rudder.

Fig. 8 illustrates the manner of guiding the rope employed for the steering along through the hollow spindle of the main ruder, a single auxiliary rudder being used. The rope 37 is introduced from above, then passed across the guide pulleys 38 arranged 1n the body of the main rudder 1, then on to the sheave/ 100f the auxiliary rudder 2'. which is likewise disposed in the body of the main rudder, and across the sheave 39, it finally passes out again below through the hollow spindle 41 of the main rudder.

result of this arrangement,'

The auxiliary rudder may be operated directly from the bridge by mechanical means. However, gear of any other kind whatsoever may be interconnected, say, f. e., hydraulic or electrical gear, or the like. It

will be found expedient to duly take care that the driving gear arranged on the bridge, and those disposed at other points of" the vessel, execute equal and equally large motions. The driving power may eitherbe a manual one, produced by the man at the wheel, or else may be supplied by sources of power of any kind desired, which the man at the wheel may switch in. transmission of power may be carried forward to one of the auxiliary rudders, or it may also be arranged to actuate a device, preferably adapted to be self-locking, lodged above the main rudder; which device thereupon will act on an auxiliary rudder by means of mechanical coupling arrangements, such as have been hereinbefore described.

If deemed desirable, two contacts or series of contacts may be connected to the spindle of the main rudder, between which there is disposed an index which, when set on the one row of contacts. will start say a motor arranged at the main rudder. and which inotor will deflect the main rudder by aid of the auxiliary rudder in the direct-ion in which the index has been moved As the main rudder attains its correct position, it

Again, the i simultaneously shifts the row of contacts away from the index, whereby this latter will again be in the central (neutral) position, and the motor switched off. Fig. 9 disclosed diagrammatically such anarrangement, in which 1 denotes the main rudder, 2 the auxiliary rudder, 42 the spindle of the main rudder, .43 the index mounted thereon, and 44, 45, respectively, the two rows of contacts. It is obvious, that in the place of a motor, also a magnet may be employed, and instead of an electrical device, a pneumatic or hydraulic device for the purposes specified.

If it b desired to operate likewise directly the freely movable main rudder, then the movements of the transmission members disone plane either one iliary rudders are counter-balanced by 'rear edge, as indicated posed co-axially to the main rudder axis may be suitably restricted relatively to the main rudder, and this in the manner indicated, for example, in Fig. 6 by means of the projection 46 the stops 47 provided on the main rudder. For certain purposes, for example in the case of river craft, it may prove important to provide the main rudder with a special auxiliary rudder for. every steering direction. In the same way,-and this for reasons of precaution, a plurality of uniformly acting auxiliary rudders may be arranged in above the other, or else in different planes, such as is disclosed in Figs. 10 and 11, respectively, in which 1 denotes the main rudder, and 2 2, 2 and 2, 2", 2, respectively, the auxiliary rudders. But also the main rudder itself may be subdivided into a number of superposed sections, each of which is operated by anauxiliary rudder (Fig. 12).

. It will be found expedient to counterbalance both the main as also the auxiliary rudder. In Fig. 13 both the main and mix- 8- ing mounted on a pivot located some distance inwardly from the front edge of ,each rudder. In this construction the front edge of the auxiliar rudder 2 on being deflected does not'pass eyond the edge of the main rudder 1. To prevent foreign bodiesfrom.

penetrating the space between the main and the auxiliary rudders,

main rudder maybe extended beyond the I tensions bein suitably shaped for allowing the ingress 0 water.

It may, moreover, appear desirable to so dispose the axis of the main rudder, that this latter, provided there were no auxiliary rudder arranged, would have to be considered up to within the proximity of the extreme deflection or even yet in this very position, as being overbalanced. Now, by the provision of the auxiliary rudder 2 (Fig. 14) in the case of such an arrangement, not only is the possibility of the said formed on disc 22, and

the sidewalls of the at 48, the said ex-.

rudder being overbalanced obviated, but in addition the control action of the main rudder 1 is considerably improved.

Figs. 15 and 16 illustrate a special manner of balancing the main and the auxiliary rudders. In this arrangement, the balancing surface 49 is separated from the rudder surface 1, while being connected to it by lever arms 50 which may pro ect from it either laterally or obliquely. And wherefact of the centre of pressure travelling across the narrow balancing surface is a moment but of minor importance, which moment most favourably affects the displacement of the centre ofpressure in respect of the whole rudder. It follows that balancing surfaces of this kind may also prove advantageous regardless of the fact whether an auxiliary rudder is provided or not. In the form of arrangement shown in Fig. 17, there are arranged at either side of the main rudder 1 (shown in dotted lines in its extreme position) the balancing surfaces 51, 52, and this by means ofobliquely disposed lever arms 53. In this construction, the one face of the balancing surfaces is so shaped as to constitute an inwardly directed convex surface. As a consequence, when in the extreme position, the one balancing surface, say 51, offers an exceptionally great resist ance to. the current, and successfully secures the rudder in its extreme position, or else assists the deflection thereof. At the same time, the other balancing surface 52 is shifted into a position in which it is enabled to create a reduced pressure on its convex and an increased pressure on its concave side. The resultant of the difference of pressure is so disposed, that the second surface will co-operate, even as the first, to retain the rudder in its extreme position, respectively, to facilitate the operation of said rudder.

However, the balancing surfaces may also be pivoted to their lever arms, and be controlled by connecting rods which, on the one hand, form contact with the vessel or the main rudder, and, on the other hand, with the balancing surface itself or a stop to which it is subject. A. form of construction of this kind is shown in Fig. 18, in which the balancing surfaces 54 are pivoted to the lever arms 55 of the main rudder 1", and which, when this latter is moved, be this either directly or by aid of an auxiliary rud- I ,v spectively.

.above and below by widely protruding suropposite direction, they adjust themselves in a line parallel to the current.

What has herein been set forth with reference to the balancing surfaces, may be applied with special effect to the auxiliary rudders. Figs. 19 and 20, disclose two forms of execution in which the auxiliary rudder is no longer subject to the immediate control of the man at the wheel, but in which its movements are made dependent upon these executed by the main rudder, the deflection of which takes place in the manner hitherto customary, and is now merely facilitated by the action of the auxiliary rudder. In the form of construction according to Fi s. 19, the auxiliary rudder 2 is connected by means of a connecting rod 58 to the hull 60, and on the main rudder 1 being turned to starboard, is shifted to larboard. In the form of execution according to Fig. 20, the connection with the hull of the vessel is established by means of a rope 61, adapted to roll up, respectively, off, on the stationary sheaves 62, 63 of the hull 60 and of the auxiliary rudder 2- respectively. In both cases, at any rate, the automatic setting of the auxiliary rudder, counter to the deflection of the main rudder, effects an acceleration and facilitates the deflection of the main rudder. The forms illustrated in these -figures are being claimed in a divisional a plic ption, Serial No; 204,517 filed July 9, 192

With the view to preventing the formation of eddies at the ed es, and also with the view to obtaining fair y high differences of pressure, there may be arranged, (and this essentially horizontally) surfaces transversely to the rudder, and this either on the rudder itself or else either above or below the same. Arrangements of this kind are shown diagrammatically in Figs. 21 and 22, in a perspective view and edge view, re-

The main rudder 1 is limited faces 64. Above and below the opening cut into the main rudder, there are arranged smaller surfaces within the aforesaid opening, the auxiliary rudder 2 to rotate. The surfaces 64 may also be arranged at the hull of the vessel, and the surfaces 65 at the auxiliary rudder.

Since the main rudder oscillates freely about its spindle, this latter may be made to be stationary relativelyto the vessel, and to constitute a portion of the ships structure. Thus, e. g., in the form of construction shown in Fig. 23, a stationary spindle is arranged between the body-of the vessel and the extension 71.

The stationary spindle may be constructed along specially favourable lines on combining it with the strengthening pieces of the hull of the vessel, as illustrated in Fig. 24 (in a longitudinal view) and Fig. 25 (in a means of the intermediate the main rudder is provided is adapted rear view).

In this form of construction,-

the spindle 72 constitutes a pivot, the broad posed within a longitudinal bore formed in the pivot 72, said shaft serving to effect the movement of the auxiliary rudder 2, by

shaft 75.

Fig. 26 illustrates a modified form of this construction, in which a hollow spindle 77,

together with the steering shaft 78, are disposed within the bore formed in the pivot 7 6. On the hollow spindle being connected to the main rudder (not shown) by means of laps 79, then one or both rudders may be steered directly, while by means of said hollow spindle the movement of one or both rudders may be transferred upwards in order to act upon the gearing, the switches etc. The hollow'spindle might as well be emformed integral with ployed to steer the auxiliary rudder, and the shaft to transfer the motion of the main rudder.

By way of a protection for the auxiliary rudders there may be arranged protective surfaces on the main rudder 1 and this transversely to the plane of the rudder, as illustrated, by way of example, in Figs. 27 and 28, in an elevation and plan view, re-

spectively, in which the surfaces 100 project beyond the auxiliary rudders 2 to such an extent, that these are most reliably secured against any injury by mechanical means.

In the arrangement according to Fig. 29, the said protective walls 101 extend only sideways of the auxiliary rudder; they are, however, also arranged on the first auxiliary rudder to protect the second, and on the second for the protection of the third, etc.

Protective surfaces 102, which are arranged perpendicularly intermediate the surfaces 101, and which may also act as guide faces complete the protection provided for the auxiliary rudders. i

In the arrangement accordin to Fig. 30,

disposed arms 103 havin perpendicular guide surfaces 104. Ont esc latter there are arranged the auxiliary steering surfaces 105, adapted to co-operate with the first auxiliary rudder at the main rudder, and with with obliquely I which they are connected by means of connecting rods 106, or the like. The auxiliary rudders thus connected are steered b the second auxiliary rudder, disposed intermediate, and protected against any possibility of injury from without. As a further means of protection, there is arranged a lattice work structure 107, the bars of which have the most favourable profile formation possible. 7 (not shown in the drawing) connect the stationary parts to arigid structure.

Horizontal protective surfaces protective surfaces 108.

' ders and the gearing freezing,

The rudder structures disclosed in Figs. 31 and 32 possess the shape of a box, through which the water is enabled to flow. WVithin this internal current the smallest and most sensitive auxiliary rudders are arranged to operate. In this arrangement the main rudder comprises three vertical surfaces 1 1 1, interconnected by means of horizontal A honeycomb: shaped structure 109 serves as a protection against foreign bodies being washed" in by the current. 20 arranged at the surface 1 are protected by means of auxiliary surfaces 110, arranged freely to move on the surfaces 1, which follow the motions executed by the auxiliary rudders, even as though they were connected thereto, since they are moved by the deflected current.

A modificationof this form of'construction is shown in Fig. 32, in which there are arranged between the three stationary surfaces l two additional stationary guide surfaces 111 along with auxiliary rudders 2 which are connected to the auxiliary rudder 2* of same size by means of guide members 112.

The main rudder actuated in accordance with my invention by means of auxiliary rudders, will be found to be particularly suitable as a bow rudder, see Fig. 33.

As a precaution against the auxiliary rudthe main rudder may be provided with steam heat or be heated electrically.

In order to enhance the sensitiveness of the auxiliary rudder, it may be shaped in the manner disclosed in Figs. 34 and 35. As will be seen, the surface of the rudder is divided into two sections 115, 116 forming an angle, intermediate which a transverse surface 117 may be interposed to prevent the formation of eddy currents. When in their normal position, the two sections possess the same though contrary angle of inclination of, say, 3 relatively to the current. If the auxiliary rudder be now shifted for, say, 3 toward larboard, then the larboard position of section 116-is increased, while the starboard position of section 115 is reduced by the value of these three degrees. section 110 is thus disposed at 6 and the section 115 at 0 relatively the normal position. If then the force acting on section 116 was at first w, it will now be in excess of 2", since the pressure curve very powerfully augments with the size of the angular position assumed, whereas the pressure on a non-intercrossed (level) rudder can never amount to more than 2.

Seeing that the auxiliary rudder arrangement hereinbefore described will not be immediately suitable for sailing astern, it will be found expedient to enable the main rudder to be set freely in any angle required,

The auxiliary rudders 2 and.

The 'tromotor 129,

so that it can turn in a full circle about its axis. This being the case, then, on the astern movement of the vessel being initiated, the main rudder will swing owing to the reversal of the current. In this contingency care must be taken that the auxiliary rudder, provided its gear be self-locking, or when, on the steering operation being effected manually, the steering wheel is to remain stationary, shall be able to rotate freely, or at least that its movement be rendered unstable or become an oscillating motion.

If the main rudder be connected to an auxiliary rudder, as shown in Fig. 36, which either serves to reset the main rudder or else to reduce the work required to be done in order to set the main rudder, then this said auxiliary rudder must be enabled to operate properly even when the main rudder has been reversed.

This may be done in accordance with my invention by various means; arrangement must be such that the motion of the main rudder will be in no way impeded by the auxiliary rudder. lln connection herewith the auxiliary rudder maybe arranged to move during a continuous movement of the main rudder in one particular direction, either continuously or non-continuously, in that either the movement of the auxiliary rudder is intercepted, or in that it is caused to execute an oscillating motion relatively th the main rudder.

In the arrangement shown in denotes the bow or stern of a vesse according to whether the rudder be arranged fore or aft, while 126 is the main rudder, and 127 the auxiliary rudder. The movement of the auxiliary rudder is also in this case preferably etfected through the spindle 128 of the main rudder. The spindle of the auxiliary rudder is unilaterally disposed, i. e. shifted out of the longitudinal centre. It follows herefrom that the rear edge of the main rudder andthe front edge of the auxiliary rudder are arranged at .a distance sufiiciently large to enable the tail end, or the head, respectively of the .auxiliary rudder to pass through in" the course of the rotation. The auxiliary rudder is driven say by an elecdriving the shaft 130 preferably across a self-locking transmission arrangement. By means of the sets of bevel wheels 131, 132, 133, 13 1 the movement is transferred on to the auxiliary rudder. The motor 129 is started in order to displace the main rudder, and it displaces the auxiliary rudder 127 against the current. As the vessel begins to sail astern, the main rudder will effect a reverse in accordance with the altered direction in which the vessel now travels and also with the flow of current, be this reverse action carried out either automatically or by aid of the auxiliary rudder, then the bevel wheel 132 will roll on wheel Primarily, the

131. The auxiliary rudder 127 continues to rotate around its axis until it has attained the new position required. The ratio of gear of the bevel wheels is so arranged that the auxiliary -i'udder will again assume its pro er position in the altered position taken up y the main rudder. This will be the case provided the ratio of gear represent a whole number. Still it will be found expedient to maintain definite values for the ratio of gear, and this for the following reasons: As will be observed from the drawings, the connection between the main rudder and the auxiliary rudder is such, that on the main rudder executing any undesirable movements, the auxiliary rudder will automatically assume a position bound to coun teract the undesirable movement of the main rudder, and thus shift this latter back into its proper position. If, for example, the rear edge of the main rudder were to rotate downwardly out ofithe plane of the drawing, then the bevel wheel 13.2 will roll on wheel 133 in such a manner that wheel 134 (viewed from the rear) will rotate to the right. In this contingency, the auxiliary rudder 127 will, by aid of the wheel 133,'be likewise rotated with its rear edge out of the plane of the drawing, and this more powerfully than the main' rudder. The current then exerts such a force upon the auxiliary rudder that the moment acting around the main rudder axis will carry the main rudder back into its initial position. It follows that for the automatic return operation, the auxiliary rudder must be set to o crate in the same direction as the main rud er, for the actual steering operation in the counter direction.

If a second auxiliary rudde be arranged, which shall act on theifirst auxiliary rudder, then the movement of this sec nd auxiliary rudder. will be the reverse of that of the first, consequently, during the automatic return action in a contrary sense to the movement of the main rudder, and' during the actual steering operation in the same sense sult will, as arule,

thereto. If more than two auxiliary rudders be employed, an arrangement which may be found to be practical in the case of 'ver big rudders, then the' odd. numbered auxi v iary rudders will follow the motion of the first, and the even numbered auxiliary rudders will follow the motion of the second auxiliary rudder. If, on the vessel reversingi its direction, the main rudder also assume a reversed sition, then the auxiliary rudder must again counteract any undesirable action on the part of said main rudder. This rebe obtained (in particular also in the arran ment shown in the drawings) whenever fife ratio of gear represents a whole number. In the form of execution shown in 36, the axis of the auxiliary rudder had been shifted to one side, out of the longitudinal centre. If now the axis of the auxiliary rudder be lodged centrally, as shown, for example, in Fig. 37, then it will not be necessary to leave any space between the front edge of the auxiliaryrudder and the rear edge of the main rudder; on the contrary, it will be found expedient to arrange the two edges as closely as possible to each other: Nor is it necessary in this case that the ratio of gear represent a whole number. In an arrangement of this kind under certain circumstances, there will arise considerable forces as soon as the auxiliary rudder moves out of the plane of the main rudder. Now to enable these forces to increase gradually, it will be found practical if one of the two abutting edges, say,

the rear edge of the main rudder, or else the front edge of the auxiliary rudder, or even the entire auxiliary rudder, obtain a curved I shape, for example, an undulated, or may be also a stepped profile formation, such as is disclosed in Figs. 38 to 40.

The arrangements shown in Figs. 36 and 37 were intended to exemplify the factfthat on the movement of the main rudder being a continuous one, that of the auxiliary rudder will also be continuous. Now, as already above set forth, there is the possibility of arranging the auxiliary rudder in such a manner that on the main rudder rotating continuously, the duxiliary rudder will move non-continuously. Thus, for example, during a continuous movement of the: main rudder, its connection with the auxiliary rudder maybe broken as soon as the main rudder, in the course of its motion, attains the inoperative zone. However, still-more expedient will be'found to be arrangements in w the case of which during the continuous mo- I tion of the main rudder in one direction, the auxiliary rudder will execute an oscillating motion relatively to the main rudder.

Aform of execution of such an arran eme t is shown in Fig. 41, in which 126 enotes the main rudder and 127 the auxiliary rudder. The auxiliary rudder is also in this case operated b means of a device arranged in the spind e 128 of the main rudder. 130 denotes the motor, driven by electricity, by hydraulic means, or the llke, and driving the set of toothed wheels 135, 136 b :aid of a self-locking gear arrangement. '1 0 toothed wheel 136 is mounted on a shaft disposed within aear box 137 ada ted to move with the rud er. The toothe wheel 136 carries a pivot 138 moving conjointly with the block 139 in the link 140 (Fig. 42). The link inudditionis provided with a rack 141 with which a toothed wheel 142,*driving the auxiliary rudder 127 by aid of a suit-' able gearin is adapted to mesh. The ratio of ear an the length ofthe rack must be so imensioned that during the movement 

